1. Field of the Invention
The present invention relates to a motion picture film and to a technique for recording and/or reproducing digital data onto and/or from a sound track of such motion picture film.
2. Description of the Prior Art
Conventional motion picture film may include picture recording regions respectively arranged in a plurality of frames at an approximate mid-portion of the film and two series or rows of film take-up holes (perforations) respectively located on either side of each picture recording region. Such motion picture film may further include a linear analog sound track located between the picture recording regions and one row of the perforations which extends in a film take-up direction. Analog signals may be recorded onto such analog sound track by the use of analog recording techniques.
Due to the recent progress in digital technology, audio information or data associated with a motion picture may be digitally recorded onto a motion picture film. However, the recording position of the picture recording regions and the analog sound track are standardized by the Society Motion Picture and Television Engineers (SMPTE), an association in the U.S.A. of motion picture and television engineers. As a result, digitized audio information or data is recorded in positions other than the picture recording regions and the analog sound track. More specifically, two digital sound tracks are provided in the film running direction of the motion picture film for recording digitized audio data therein and for reproducing the recorded digitized audio data therefrom. Each of such digital sound tracks is located between the perforations and a respective one of the lateral film edges. The audio data includes audio data for a right channel and audio data for a left channel which are each respectively recorded in a linear manner in one of the two digital sound tracks. Each of such audio data includes synchronization data, audio data and tracking patterns which are recorded in a direction normal to the film running direction in the digital sound tracks. The synchronization data or pattern is formed at the leading end of a block made up of a predetermined number of data followed by the audio data which is recorded block-by-block. The tracking patterns are recorded at each of the recording start and the recording end portions. Such tracking patterns are recorded in stripes on both sides of the digital sound tracks extending along the film running direction.
A reproducing apparatus for reproducing the digitized audio data from the motion picture film may include two CCD line sensors adapted for scanning the digital sound tracks so as to respectively read out the audio data recorded in the channels. Each of the CCD line sensors has a one-line reading region and is arranged so as to read such line in a direction normal to the film running or proceeding direction. During reproduction, light is radiated from the back surface of the motion picture film. As a result, the synchronization data, audio date and the tracking patterns recorded on the digital sound tracks of the motion picture film are illuminated and radiated on the reading regions of each of the CCD line sensors.
The CCD line sensors receive the illuminated synchronization data, audio data and the tracking patterns and convert them into electrical signals which are supplied to a data processor included in the reproducing apparatus. The data processor reproduces the audio data on a block basis in synchronization with the synchronization data and routes the reproduced audio data to a digital-to-analog (D/A) converter, which may be included in the reproducing apparatus, so as to convert the audio data to analog audio signals. Such analog audio signals may be thereafter supplied to a speaker unit. As a result, the speech corresponding to the digital audio data is provided by way of the speaker unit.
As previously described, the data processor receives signals corresponding to the tracking patterns from the CCD line sensors. Such signals are utilized by the data processor to provide tracking control data. More specifically, the tracking pattern is recorded at the recording start position and the recording end position for one-line of audio data. The data processor detects a level difference between, for example, the tracking pattern reproduced at the recording s;tart position and that reproduced at the recording end position, so as to determine or detect a tracking error. The readout timing of the CCD line sensor is variably controlled in response to the tracking error. As a result, tracking error may be corrected so as to effect reproduction of the audio data at all times in the so-called just-track condition.
As is to be appreciated, scratches may be produced on the motion picture film. Such scratches may be identified or classified as longitudinal scratches which extend along the film running direction and transverse scratches which extend in a direction substantially normal (or at right angles to) the film running direction. Due to the manner in which the motion picture film is typically handled and/or moved, longitudinal scratches are produced therein more frequently than transverse scratches.
The longitudinal scratches may adversely affect the reproduction of digital audio data recorded on the conventional motion picture film. That is, audio data and so forth are recorded in the digital sound tracks of such motion picture film in a direction normal (at right angles to) the proceeding direction of the motion picture film. As a result, longitudinal scratches may cause the destruction of audio data across a plurality of lines, thereby making the reproduction thereof relatively difficult, if not impossible, to obtain and/or reducing the quality of the reproduced data. Further, the transverse scratches may also adversely affect the reproduction of the audio data.
Thus, the prior art has failed to provide a motion picture film and/or a technique for recording digital audio data on a motion picture film such that scratches, such as longitudinal and transverse scratches which may be produced on the film, do not adversely affect the reproduction of the recorded digital audio data.